The invention relates to a method of producing a total image of the environment surrounding a motor vehicle by using an image sensor device connected with the motor vehicle, which supplies image data in a first acquisition range of the vehicle environment.
Multiple methods of this type are known in the prior art. For example, image sensor devices are also known, where, for enlarging the effective acquisition range of the image sensor device, the individual pictures of several individual cameras are assembled to form a total image. International patent document WO 03/051671 A1 describes such an image sensor device using the example of a back-up camera.
For providing a large acquisition range of such an image sensor device, either very expensive wide-angle cameras have to be used or a sufficiently large number of individual cameras have to be arranged on the motor vehicle such that at least the combined number of individual acquisition ranges covers the total acquisition range desirable for a certain application. Very wide-angle camera systems usually have the disadvantage of considerable image distortions particularly in the edge regions of the image. The use of additional cameras, in addition to the often considerable costs for the cameras themselves as well as for suitable image processing on the output side, also has the disadvantage that, in many cases, a suitable mounting of the cameras on the motor vehicle is not easily achievable.
Particularly, the inclusion of the environment region situated in front of the vehicle front end into the acquisition range, for example, for the purpose of producing a complete panoramic-view image, requires the mounting of a camera on the vehicle front end. However, the mounting of a camera on the vehicle front end may be connected with design disadvantages and usually requires very high technical expenditures. A front-end camera must have a rugged design in view of the considerable external influences acting upon the vehicle front end and, under certain circumstances, may require a mechanical protection device. Providing a front-end camera is, therefore, technically difficult and, as a rule, costly.
Without a front-end camera, however, the acquisition range of the image sensor device that is obtained is not satisfactory for many applications. The same or similar problems exist with respect to the inclusion of the region of the surrounding environment situated behind the vehicle rear in the acquisition range, because also providing a rear camera on a motor vehicle, as a rule, requires high technical expenditures and may be connected with design-related disadvantages.
It is an object of the invention to provide a simple method by which a total image of the surrounding environment of a motor vehicle can be produced in a large acquisition range at low expenditures.
This object is achieved by a method of producing a total image of the surrounding environment of a motor vehicle by using an image sensor device connected with the motor vehicle, which supplies image data in a first acquisition range of the vehicle environment. At least a first image part of the total image is based on image data of the image sensor device from the first acquisition range. In addition to the image sensor device, a distance sensor device connected with the motor vehicle is used which supplies distance data in a second acquisition range of the vehicle environment. The second acquisition range covers an additional range of the vehicle environment which is not covered by the first acquisition range. At least a second image part of the total image, which is at least partially situated outside the first image part, is based on distance data of the distance sensor device from the additional range. Advantageous embodiments and further development of the invention are described herein.
According to the invention, a total, complete or full image is produced on the basis of image data of the image sensor device as well as on the basis of distance data of a distance sensor device provided in addition to the image sensor device. The distance sensor device that is used in addition to the image sensor device supplies distance data in an acquisition range or zone of the vehicle environment which differs from the acquisition range of the image sensor device. In particular, the acquisition range or zone of the distance sensor device covers an additional range or zone of the vehicle environment which is not covered by the acquisition range of the image sensor device. The distance data relating to this additional range can therefore be used for generating an additional image part in the total image, which represents the additional range. On the basis of the distance data of the distance sensor device for the additional range, the additional image part can visualize the distance relationships between the motor vehicle and objects in the vehicle environment and can promote an estimation of the risk potential in the additional range.
By way of the method according to the invention, a total image can be produced whose effective acquisition range exceeds the acquisition range of the image sensor device without requiring further image sensors, particularly cameras.
When the invention is appropriately implemented, the use of a distance sensor device can even achieve improved effective display precision in comparison to the use of very wide-angle cameras, because camera images taken with a wide angle are distorted considerably in the edge areas and are difficult to correct. The invention offers an elegant solution for “closing gaps” in camera-based monitoring of the vehicle environment, which is superior to an excessive development of the camera and image processing technology with respect to precision and cost.
The invention utilizes a distance sensor device. Distance sensor devices are currently widely available and are cost-effective. Particularly, with respect to the equipment, the distance sensor device used according to the invention can be implemented such that, without the presence of cameras, it can also be used independently as a distance generator for a driver assistance system. This further development makes it possible for vehicle manufacturers, for example, to offer their customers the distance sensor device as a basic equipment variant and to offer the expanded system operated according to the invention as optional equipment without having to modify the distance sensor device between the two variants with respect to the equipment.
According to a preferred embodiment of the method of the invention, the distance information concerning the additional range is converted to a virtual image of the additional range. The generating of the image part or sector representing the additional range can basically take place in the same or a similar manner as currently known for driver assistance systems functioning exclusively on the basis of a distance sensor system. For example, systems and methods are currently known by the name of “Park Distance Control” (PDC), in which a virtual image of the vehicle environment, possibly including an image of the vehicle itself, is generated from a bird's eye view. In this image, the regions of the vehicle environment are marked and, as necessary, divided into several distance stages by colors or in a different manner. The ultrasound-based detection of objects in these monitored regions of the vehicle environment has the result that, in the virtual image, the corresponding image regions are stressed by changes in the color and/or brightness. The presence of the objects is thereby visualized in the virtual image of the vehicle environment. In this fashion, the user of such a system or method is visually informed of distance data.
According to the invention, the total image is produced as a combination of the first image part or sector based on image data of the image sensor device and of the additional second image part or sector based on image data of the distance sensor device. If, for the production of the second image part, an image is available, which can be constructed, for example, as a virtual image of the vehicle environment—particularly of the additional range, the total image can be generated in a manner known per se by assembling the image parts. For example, in a panoramic view system, a virtual image of the front-end range based on distance data can then be integrated in the total image instead of the image of a front end camera (or its perspective transformation). In this case, the front end range represents the additional range according to the present invention.
In the total image, the transitions between the used partial images can be constructed as directly visible section edges. Technically, this is the simplest solution which, because of the different character of the individually image parts existing anyhow (typically real image or photo-realistic image in the case of the first image part vs. typically virtual image in the case of the second image part), results in only a slight impairment of the aesthetics of the total image.
Nevertheless, as an alternative, a soft fade-over between the partial images may be provided in order to avoid such visible section edges and to provide a soft visual transition between the first and the second image part in the total or overall image. Depending on the viewer's preference and degree of experience, this manner of display can let the total image appear clearer and have the effect of facilitating a viewer's intuitive interpretation. Under certain circumstances, this may also permit a more pleasing display format with respect to aesthetic aspects. Fade-over effects may have the same results at the edges of the image parts.
The partial images of the image sensor device and of the distance sensor device respectively overlap. Visible section edges can then be defined in a suitable manner—particularly in an aesthetically pleasing manner. Fadeovers are made possible only by an overlapping.
Another possibility of treating overlapping partial images of the image sensor device and of the distance sensor device respectively is the superimposition of the partial images. For example, in the overlapping area, a virtual image, which visualizes the distance information supplied by the distance sensor device, can be superimposed with high transparency on a photo-realistic image, which is generated on the basis of image date of the image sensor device. In the overlapping area, a photo-realistic image augmented by the distance information is thereby displayed to the user.
The invention should naturally also be considered to be advantageous to an unchanged extent when the partial images do not overlap or adjoin one another. For a better utilization of the video screen when the partial images do not adjoin one another, the intermediate regions, as required, can be displayed in reduced size in comparison to the covered ranges of the vehicle environment.
According to the invention, the image sensor device can include one or more cameras. When several cameras are used, the first image part of the total image, which is based on image data of the image sensor device, may be composed of several partial images of individual cameras. The distance sensor device preferably also includes several sensor components. The image parts according to the invention may each include one cohesive image region or several individual image regions.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.